如何删除核心数据SwiftUI？ [英] How to delete Core Data SwiftUI?
本文介绍了如何删除核心数据SwiftUI？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
很抱歉这个愚蠢的问题，但我已经搜索了大约两天的答案，并尝试了许多方法来处理它。
我在核心数据上运行的WatchOS应用程序。有3个视图：
- 第一视图-包含用于添加新目标和已添加目标列表的按钮的视图。
- 添加目标视图-按"添加新目标"后显示。
- RingView-带有目标环的视图(类似于活动环机制)和显示的所有数据。
因此，我尝试让用户有机会直接在第一个视图中删除创建的目标。在不同的迭代之后，我了解到，删除按钮在RingView中起作用，但在第一个视图上不起作用。您能谈谈您对这个问题的看法吗(如果可以，请给出一个.onDelete变体)？
以下是我的Firstview代码：
struct FirstView: View {
@Environment(.managedObjectContext) var context
@Environment(.presentationMode) var presentationMode
@FetchRequest (
entity:NewGoal.entity(),
sortDescriptors:[NSSortDescriptor(keyPath: NewGoal.dateAdded, ascending: false)],
animation: .easeInOut )
var results:FetchedResults<NewGoal>
var body: some View {
ScrollView{
VStack{
VStack(alignment: .leading){
NavigationLink(
destination: AddGoalView(),
label: {
Image(systemName: "plus")
Text("Set Money Goal")
})
.frame(maxWidth: .infinity)
.clipShape(RoundedRectangle(cornerRadius: 9))
VStack(alignment: .leading){
ForEach(results){ item in
NavigationLink(
destination: RingView(goalItem: item, GTitle: item.goalTitle ?? "", Sum: item.neededSum, summarize: item.yourSum),
label: {
HStack{
Button(action: deleteGoal){
Text("Delete") } //// < --- Here it is
Text(item.goalTitle ?? "")
Text("$(item.yourSum, specifier: "%.f")")
Text("/ $(item.neededSum, specifier: "%.f")")
}
}) .contentShape(Rectangle())
.clipShape(RoundedRectangle(cornerRadius: 9))
}
}
}
}
}
}
/////MY DELETE FUNC
private func deleteGoal(){
let goal = NewGoal (context: context)
context.delete(goal)
do{
try context.save()
presentationMode.wrappedValue.dismiss()
} catch let err{
print(err.localizedDescription)
}
}
}
以下是我的RingView代码(一切正常)：
struct RingView: View {
@State private var isFocused = false
@State private var isFocusedSum = false
@State private var name: String = ""
@State var dayindex = 0
@State private var yournewSum:Double = 0.0
var goalItem: NewGoal?
var GTitle:String
var Sum:Double
var summarize:Double
var allNewSum:Double = 0.0
@Environment(.managedObjectContext) var context
@Environment(.presentationMode) var presentationMode
@FetchRequest var results: FetchedResults<NewGoal>
init(goalItem: NewGoal? = nil, GTitle: String, Sum: Double, summarize: Double, allNewSum: Double){
self.GTitle = GTitle
self.Sum = Sum
self.goalItem = goalItem
self.summarize = summarize
self.allNewSum = allNewSum
let predicate = NSPredicate(format:"goalTitle == %@", GTitle)
self._results=FetchRequest(
entity: NewGoal.entity(),
sortDescriptors: [NSSortDescriptor(keyPath: NewGoal.dateAdded, ascending: false)],
predicate: predicate,
animation: .easeInOut
)
}
var body: some View {
NavigationView{
ForEach(results) { item in
ZStack{
RingShape()
.stroke(style: StrokeStyle(lineWidth: 11, lineCap: .round))
.fill(AngularGradient(gradient: Gradient(colors: [.red, .pink, .red]), center: .center))
.opacity(0.35)
RingShape(percent:(((yournewSum + summarize)/Sum*100)+0.1), startAngle: -90, drawnClockwise: false) ///FG Ring SUM
.stroke(style: StrokeStyle(lineWidth: 11, lineCap: .round))
.fill(AngularGradient(gradient: Gradient(colors: [.red, .pink, .red]), center: .center))
RingShape() ///BG Ring Date
.stroke(style: StrokeStyle(lineWidth: 4, lineCap: .round))
.fill(Color.yellow)
.opacity(0.35)
.frame(width: 145, height: 145)
RingShape(percent: (Double((item.pickedValueDateN - item.pickedValueDateN1)*100) / (Double(item.pickedValueDateN) + 1) + 0.1), startAngle: -90, drawnClockwise: false)
.stroke(style: StrokeStyle(lineWidth: 4, lineCap: .round))
.fill(Color.yellow)
.frame(width: 145, height: 145)
///BUTTON
HStack(alignment: .top){
Spacer()
Button(action: addSum) {
Image(systemName: "checkmark.circle")
.font(.title3)
.opacity(1)
} .buttonStyle(MyButtonStyle())
.frame(width: 30.0, height: 30.0)
.clipShape(Circle())
.disabled((yournewSum + summarize) <= summarize)
}
.padding(.bottom, 135.0)
.padding(.horizontal, 8.0)
VStack(alignment: .trailing, spacing: 0.0){
Spacer()
Text("$((yournewSum + summarize), specifier: "%.f")")
.font(.title3)
.bold()
.padding(4)
.overlay(
RoundedRectangle(cornerRadius: 7)
.stroke(Color.white, lineWidth: 2)
.opacity(isFocusedSum ? 1.0:0.0)
)
.focusable(true) { newState in isFocusedSum = newState}
.animation(.easeInOut(duration: 0.3), value: isFocusedSum)
.digitalCrownRotation(
$yournewSum,
from: 0,
through: Double((Sum - summarize)),
by: 10,
sensitivity: .high
)
Text("/ $(item.neededSum, specifier: "%.f")")
.font(.caption)
.foregroundColor(Color.gray)
.padding(3.5)
Button(action: deleteGoal){
Text("HO")
}
Spacer()
}
.frame(width: 200, height: 230)
.padding(.top, 15)
}
}
.padding([.top, .leading, .trailing], 5.0)
}
}
private func addSum(){
let goal = goalItem == nil ? NewGoal(context: context): goalItem
goal?.yourSum = yournewSum + summarize
goal?.allNewSum = yournewSum + allNewSum
do{
try context.save()
presentationMode.wrappedValue.dismiss()
} catch let err{
print(err.localizedDescription)
}
}
private func deleteGoal(){ //// < -- Here it works
if let goal = goalItem {
context.delete(goal)
do{
try context.save()
presentationMode.wrappedValue.dismiss()
}catch let err{
print(err.localizedDescription)
}
}
}
}
推荐答案
按如下方式更改删除方法
private func deleteGoal(goal: NewGoal){
context.delete(goal)
do{
try context.save()
presentationMode.wrappedValue.dismiss()
}catch{
print(error)
}
}
并将您的按钮更改为此
Button(action: {
deleteGoal(goal: item)
}){
Text("Delete") }
这篇关于如何删除核心数据SwiftUI？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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